There are already software specialized for this such as the mizu VoIP tunneling and encryption which works with the SIP/RTP protocols: https://www.mizu-voip.com

There are already software specialized for this such as the mizu VoIP tunneling and encryption which works with the SIP/RTP protocols: https://www.mizu-voip.com/Software/VoIPTunnel.aspx https://www.mizu-voip.com/Software/VoIPTunnel.aspx